TT #5 · Parshas Tazria · Aliyah 1 · Passuk 2
English: Speak to the Israelite people thus: When a woman at childbirth bears a male, she shall be impure seven days; she shall be impure as at the time of her condition of menstrual separation.
Chabad.org — Chumash, English translation + Rashi for Vayikra 12:2
Torah Temimah cites Niddah 31a.
English: Rabbi Yitzchak said in the name of Rabbi Ami: If the woman emits seed first, she gives birth to a male; if the man emits seed first, she gives birth to a female, as it says: “If a woman conceives and gives birth to a male.”
Textual inference
The sequence of “she conceives” and “gives birth to a male” is read as a scriptural allusion to the order of conception.